Upgrade via replacement. We wouldn"t give you anything less than the best. Grade A cells chosen from among the top 10%. Rigorous inspection tests to ensure reliability. A built-in IC chip to prevent against short-circuiting. Complete NFC functionality. What does this all mean? In terms of quality, you won"t find a better replacement. Don"t just take our word for it, though - type in any quick, power-related search on Amazon and see who pops up. As the leader in our industry for the last 3 years running, we know batteries. While you"re at it... For the fastest and most reliable charging of your smartphone and other devices, consider Anker"s new line of 18W adapters, available for both car and home. Get to know us. Here at Anker, we"re dedicated to making the smart life easier. As a Top Rated Brand on Amazon, we"ve established ourselves as a leader in the field, bringing innovative and reliable technological solutions to millions of users across the globe. Our Astro line of external batteries has been voted #1 in class by thousands of online reviewers and praised by tech bloggers, while our renowned customer service team has made us a fan-favorite across the web. With every sale, we include an 18-month, worry-free guarantee to demonstrate the importance we set on quality. After all, we"re customers too. Compatible Models: Samsung Galaxy S4, S IV, GT-I9505, GT-I9500, Galaxy J, SGH-M919(T-Mobile), SCH-I545(Verizon), SGH-I337(AT&T), SPH-L720(Sprint), SCH-R970(U.S. Cellular/MetroPCS) Not for Galaxy S4 Active Notes: This replacement battery is slightly thicker than an original S4 battery, but the difference in thickness does not affect use.